Shark Week Special: You're Swimming with Thousands of Sharks and that's Awesome!
Recently, I took a trip to Charleston, SC to catch sharks from the beach. When I caught a sandbar shark (Carcharhinus plumbeus) from the surf, many of the beachgoers got out of the water, not out of fear, but out of curiosity. For many of them, it was their first time seeing a shark in the wild, so they had had many questions about the shark (and wanted to touch it). I told them that summer is the perfect time of year to catch sharks from beaches in the Carolinas because that’s where blacktips (Carcharhinus limbatus) and other shark species migrate.
Then, I let the shark go, most of the onlookers cheered at the safe release of this beautiful animal, and then promptly returned to the water. While most people had no issue swimming with many small-medium sharks mixed in with the swimmers, one woman came up to me, saying how I am attracting all of the sharks to the beach and that I am going to get all of the swimmers killed. This post is to address the concerns of that woman, as well as others who are not familiar with the annual east coast shark migration or are scared of going in the water because of sharks.
Each winter, tens of thousands of blacktip sharks (as well as other similarly-sized species, like sandbar sharks, but most research focuses on the blacktips) aggregate along the beaches of Palm Beach County, Florida, where the Gulf Stream comes in close proximity to the shore. This giant aggregation of sharks signals the beginning of their annual spawning migration to the Carolinas. According to Dr. Stephen Kajiura, professor of biology at Florida Atlantic University, their migration is strongly tied to water temperature.
The ideal water temperature for blacktip sharks is 21-25˚C (70-77˚F), which is approximately the water temperature off southeast Florida during late January-March. When the water begins to warm up in April, 99% of the sharks migrate north to cooler waters (Kajiura and Tellman, 2016). The blacktips finish their migration around the Carolinas in the summer, where their nursery grounds occur. There, the sharks give birth just off the beaches, and feed on spawning aggregations of baitfish like menhaden.
So, there are tons of sharks at the beach in Florida in the winter and the Carolinas in the summer, but why are shark attacks still extremely rare? There are two main reasons, according to Dr. Kajiura: 1) humans are not on the menu for these relatively small sharks (typically no more than 2 meters/6 feet). They have small teeth that are optimized for grabbing little fish, not for cutting thick bones or tearing off large chunks of flesh. 2) We give off different sensory signals than their prey.
Even in murky water where the sharks can’t see well, humans give off different vibrational and electrical signals than small baitfish. We come off as enormous, sloppy, noisy beasts to them, which actually scares them away from us. However, shark attack frequencies do increase during the migration, particularly in north Florida to the Carolinas, where the water is murky.
The sharks may mistake hands and feet for small fish, and bite out of mistaken identity. To reduce your (already low) chances of getting bitten by a shark during the migration, simply avoid wearing shiny jewelry in the water, don’t swim at dawn and dusk, and stay away from schools of bait. These sharks are fairly small though, so while blacktip sharks are responsible for the most shark attacks in the country, none of these attacks are fatal.
Now, is it safe to fish for sharks from the beach with swimmers around? More-or-less, the answer is yes! If you are using a single piece of bait on a hook, that would be a very discrete sensory cue to sharks, so it would be easy to localize on the bait. However, DO NOT CHUM if there are people in the water. Chumming puts non-discrete scents in the water that can stir the sharks up into a frenzy, and it can make the swimmers smell like baitfish.
If you are using a single bait, though, as long as you don’t cast your bait right next to swimmers, there won’t be any additional shark threat. I recommend finding a gap between swimmers in the water, wading out a bit (about to waist-depth, unless you wiped your hands covered in bait scent on your shorts, then walk out to shin-depth), and casting just behind the breaking waves, where there probably won’t be any swimmers or surfers. Many of the sharks will be waiting there to ambush prey that gets stunned in the surf, so it’s also the best place to put your bait.
One fisherman on the beach is not going to attract thousands of sharks to the area; the sharks are already there, and that fisherman will just show you what’s already in the water. Consider the huge number of people in the water, the huge number of sharks in the water, and the extremely low number of shark attacks. You’re more far more likely to choke to death on a hot dog at the beach than get killed by a shark, even during the migration. “Don’t sweat it,” says Dr. Kajiura, shark biologist, “and just enjoy the beach!” You were having a great time until you saw the shark (which was harmlessly there all along), so instead of letting it ruin your beach day, see it as a highlight, a chance to observe a beautiful animal in the wild!
Noah Bressman is a PhD candidate studying fish biology, functional morphology, and biomechanics at Wake Forest University. Below is Noah with a Sandbar Shark (Carcharhinus plumbeus), caught on a dead menhaden shad with 30 lb. test steel leader and a circle hook from a beach in Charleston, SC.
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References: Kajiura, S. M., & Tellman, S. L. (2016). Quantification of massive seasonal aggregations of blacktip sharks (Carcharhinus limbatus) in Southeast Florida. PloS one, 11(3), e0150911.